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From: Henry Spencer <>
Subject: Re: Skylab Reactivation
Date: Mon, 19 Feb 1996 15:24:03 GMT

In article <Pine.SOL.3.91.960218150130.10112A-100000@spacelink> Richard
David Glueck <> writes:

>Had Skylab survived until the shuttle program was underway, it would have 
>been interesting to see how aggressively the station might have been 
>boosted, and if in fact, it would have been occupied again.  I can't 
>believe that it's useful service lifetime was worn out due to occupancy.

Actually, yes it was, because Skylab was not really designed to be 
resupplied or maintained in orbit.  Major work would have been needed
to make it serviceable again for prolonged occupancy.  Not that this
was impossible, but it was a big enough job that it's not at all clear
that NASA would have bothered.

>The other question I have about space stations is whether or not Von 
>Braun's rotating ring design has ever been examined at length as a 
>solution for permanent occupancy in space.

Not in recent times.  The problem with the "big wheel" station is that it
basically assumes that most of the occupants have desk jobs -- watching
screens and pushing buttons -- and hence can spend their time in the wheel
without ever leaving it.  This leads to a space station which is mostly a
1G environment with only minor free-fall sections.

Trouble is, our electronics technology has advanced greatly since the days
when this looked reasonable; the desk jobs are located on the ground now. 
The rationale for putting most of the habitable volume at 1G has vanished.
Most of the things the crew would be doing are things for which free fall
is either necessary or at least an advantage.  (In addition, fears about
medical effects of free fall have mostly proved groundless.  And if you
ask the astronauts, you find that they prefer free fall and don't want 
artificial gravity.)

A further complication is that von Braun underestimated the inner-ear
problems of rotation.  Current opinion is that the wheel would have to
be very large, with a radius of hundreds of meters, to get 1G without
excessively high rotation rates.
Space will not be opened by always                 |       Henry Spencer
leaving it to another generation.   --Bill Gaubatz |

From: Henry Spencer <>
Subject: Re: Skylab 2 rescue mission
Date: Sun, 14 Jul 1996 20:56:18 GMT

In article <4s6osl$> writes:
>I was watching Nasa select last night about the Skylab program where they
>talked about a modified Apollo CSM for a possible rescue mission. (Skylab 2)
>Does anyone know what was modified and what happened to that CSM after
>it was determined the flight was not needed?

The rescue variant of the CSM basically had five couches rather than three,
exploiting the unused space underneath the Apollo couches.  (The unused space
was there to permit very long travel in the couch shock absorbers, but in
fact the shock-absorber travel for a normal touchdown was negligible, so the
rescue configuration simply locked them.)  A crew of two was enough to handle
the CSM systems, and of course there were three astronauts to be rescued.

There wasn't a specific CSM dedicated to this.  What there was, was a kit
of modification hardware, to be installed in the handiest CSM (generally
the one being readied for the next Skylab crew) if rescue was needed.
Because Skylab had such large reserves of consumables, there was no great
hurry about putting a rescue mission together.

When there were indications of trouble with the second Skylab crew's CSM
(by the way, this was technically Skylab 3 -- Skylab 1 was the launch of
Skylab itself), rescue preparations started, but before they got very far,
the problem was deemed to be under control and preparations were cancelled.
If we feared danger, mankind would never           |       Henry Spencer
go to space.                  --Ellison S. Onizuka |

From: Henry Spencer <>
Subject: Re: Wet vs. Dry Workshop Decision (Was Re: Using External Tanks of 
	Shuttle for Space Station)
Date: Wed, 31 Jul 1996 19:57:48 GMT

>>Re. Skylab, wasn't the real reason why it was switched from the Saturn IB
>>to a surplus Saturn V, that there wasn't enough rockets (and money-) left
>>for the original 'wet workshop' plan...?

According to what I've seen, the dominant problem was not so much the
rocket supply -- at this point, NASA had not entirely given up on
re-opening the Saturn production lines -- as simply the time and effort
and uncertainties of outfitting the wet workshop in orbit.  They were
hitting a lot of problems trying to make the wet-workshop concept work,
and the dry-workshop concept avoided all that. 

>The deadlock was obviated with Webb's resignation in October of 1968 and the 
>week after Apollo 11 returned form the first moonlanding, NASA officially 
>announced the switch. 

Note, though, that it was another six months before the cancellation of
Apollo 20 was announced!  The dry-workshop decision was made at a time
when NASA still held out some hope for further Saturn production.
 ...the truly fundamental discoveries seldom       |       Henry Spencer
occur where we have decided to look.  --B. Forman  |

From: Henry Spencer <>
Subject: Re: Von Braun and Wet Skylab (Was Re: JPL Apollo/Mars proposal??)
Date: Mon, 27 Jan 1997 17:51:55 GMT

(Inappropriate newsgroups deleted from Newsgroups header.)

In article <>,
Graham Nelson  <> wrote:
>I've seen references to this several times, but don't know what the
>issues are.  What do "Wet" and "Dry" mean in this context? ...

The original Skylab concept was to move into the spent S-IVB second stage
of a Saturn IB in orbit, refitting the large hydrogen tank as crew
quarters and lab, after venting the tank to clear any fuel residue.  The
idea was not unworkable -- even after the changeover, von Braun commented
that he thought the Wet Workshop could have been done, given a determined
effort -- but it required a lot of in-orbit work and added a lot of

When Apollo's primary objective was clearly taken care of, it became
possible to allocate a Saturn V to Skylab.  That made it possible to do
the refitting on the ground, and launch Skylab fully equipped, because the
two lower stages of the Saturn V were sufficient to put a fairly heavy
load into orbit.  (In fact, this way there was no particular requirement
that Skylab be built using an S-IVB, but that was the simplest approach,
especially given the work that had already been done on it.)  Hence the
"Dry Workshop" -- no fuel in the tank.

Dept of Lost Opportunities:  launching Skylab fully equipped meant that
the S-II stage also went into orbit.  Had NASA been a bit more ambitious,
and had the program been a bit better funded, it would have been possible
to kill two birds with one stone:  leave the S-II attached to the S-IVB,
with the S-IVB functioning as a fully equipped lab and the S-II available
for experimenting with moving into a spent rocket stage.  The S-II dwarfed
the S-IVB...

(As it was, the S-II separated from Skylab after orbit insertion, and
being much lighter -- just a spent stage, with no equipment aboard -- it
came down more quickly.  Incidentally, this stage -- the single biggest
object ever placed in orbit -- reentered over Africa to the accompaniment
of no media attention whatsoever.)
"We don't care.  We don't have to.  You'll buy     |       Henry Spencer
whatever we ship, so why bother?  We're Microsoft."|

From: (Henry Spencer)
Subject: Re: Apollo Crew Size
Date: Sun, 17 Jan 1999 02:24:46 GMT

In article <77qjmm$qo3$>,
Magnus Olsson <> wrote:
>In article <>, Tom  <> wrote:
>>...On Skylab, where the CSM was
>>essentally unused after the first day, the cryos still ran out around
>>the 18th to 21st day in space due to boiloff.
>Didn't the missions last longer than 21 days? Was the SM just dead weight
>when it was time to go home? And didn't they need cryos to deorbit?

Yes, the missions lasted more than 21 days.  The Skylab CSMs were modified
in a number of small ways, including extra batteries for return power and
(if memory serves) an extra compressed-oxygen tank for return breathing.
(The CM had batteries and compressed oxygen anyway, but I believe they
added more.)  Given those changes, having the cryo tanks boil dry early
in the mission was acceptable.
The good old days                   |  Henry Spencer
weren't.                            |      (aka

From: (Henry Spencer)
Subject: Re: Why using the STS external tank as a space "hotel" or station 
	module won't work......
Date: Tue, 23 Mar 1999 14:32:20 GMT

In article <>,
Cary Martynuik  <> wrote:
>...that does NOT count (the thought of retrofitting one in
>orbit after it had been used had been bounced around, but there were no
>design features in an S-IVB stage which were implemented specifically to
>make an "orbital" retrofit easier.).

Not *quite* true, actually.  The access manhole at the top of the LH2 tank
was enlarged to make it easier to do that.  (There were technical reasons
why a change to the structure in that area was needed, but that's why that
*particular* change was chosen out of several possibilities.)

Note also that a "wet workshop" S-IVB, intended for refit in orbit, would
not have been a standard off-the-shelf S-IVB.  Some internal fittings
would have been in place ahead of time.  Traces of this survived in the
final design of Skylab; for example, the metal-grid floors originated as
flooring which could be put in place in advance, without interfering with
the function of the tank.

Wernher von Braun, for one, thought that the "wet workshop" (in-orbit
refit) concept could have been made to work.  The switch to "dry workshop"
(launch fully equipped) happened because it looked easier and cheaper, not
because the wet workshop looked infeasible.
The good old days                   |  Henry Spencer
weren't.                            |      (aka

From: (Henry Spencer)
Subject: Re: Why using the STS external tank as a space "hotel" or station 
	module won't work......
Date: Thu, 25 Mar 1999 15:34:02 GMT

In article <7dcod3$phs$>,
Justin Wigg  <> wrote:
>If Apollo Applications/Skylab had gone with a wet workshop, would the crew
>have been launched on the same Saturn IB as the workshop?

No.  Some early proposals did work that way, but it became clear pretty
quickly that a useful space station -- as opposed to just a pressurized
empty tank, which some of the early ideas aimed for -- was going to need a
lot of equipment, and the Saturn IB's lift capacity was none too large.
Particularly once it became clear that a useful wet-workshop station
needed a multiple docking adapter to permit external modules to be
attached, the payload capacity of the wet workshop's own launch was fully
spoken for.  So it was one launch for the workshop, and another for the
crew (plus still another for the Apollo Telescope Mount, originally meant
to be the first external module).
The good old days                   |  Henry Spencer
weren't.                            |      (aka

From: (Henry Spencer)
Subject: Re: Nerds in Space
Date: Thu, 2 Nov 2000 00:03:22 GMT

In article <8tpseb$f8f$>,  <> wrote:
>Would metal-cored dice rolled on a large magnetic mat
>provide an adequate substitute for gravity, or would metal
>dice and flat magnetic field interact in significantly
>different manner than dice and gravity?

Hmm, possibly...  A better approach might be relatively large, lightweight
dice rolled on a big flat air filter, with airflow into the filter.

(Skylab had a couple of such filters as part of its life-support system,
and the astronauts found that they made good workbenches -- tools and
small parts could be put down on them and wouldn't float away.)
Microsoft shouldn't be broken up.       |  Henry Spencer
It should be shut down.  -- Phil Agre   |      (aka

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